Question: The arithmetic sequence $(a_i)$ is defined by the formula: $a_i = 7 + 2(i - 1)$ What is $a_{5}$, the fifth term in the sequence?
Answer: From the given formula, we can see that the first term of the sequence is $7$ and the common difference is $2$ To find $a_{5}$ , we can simply substitute $i = 5$ into the given formula. Therefore, the fifth term is equal to $a_{5} = 7 + 2 (5 - 1) = 15$.